1. Field of the Invention
The present invention relates to an image forming apparatus and an image processing method for an image forming apparatus using a color profile.
2. Description of the Related Art
Multi-function digital copiers, such as a multi-function digital copier 101 shown in FIG. 1, are known as image forming apparatuses for inputting and outputting images. The multi-function digital copier 101 can carry out multi-functional image processing using a copy function, a printer function, and a facsimile function.
FIG. 1 is a block diagram illustrating the system configuration of such an image forming apparatus. This full-color multi-function digital copier includes a scanner 103 for scanning a document image recorded on, for example, paper and a printer 104 for outputting a scanned image or an image transferred from a host computer on a medium, such as paper. The full-color multi-function digital copier further includes a device controller 105 for controlling the operations of the scanner 103 and the printer 104 and carrying out a variety of image processing, an operation unit 102 for allowing a user to operate the apparatus, and a memory 106 and a hard disk 107 for temporarily or permanently storing image data and a processing program.
Such a full-color multi-function digital copier can not only copy a document image but can also carry out a variety of image processing while copying. For example, the full-color multi-function digital copier can provide various image processing operations, such as a negative to positive image conversion function that converts black to white and white to black in a document, a trimming function that copies only part of a document, and a reduced layout function that reduces a plurality of documents and combines them onto one output sheet of paper.
Additionally, an image forming system is proposed in which the image forming apparatus is connected to a host computer via a controller and a color image created by the host computer is converted into a rasterized image by the controller to be stored in a memory in the controller. Then, the image is printed by the image forming apparatus functioning as a color laser printer.
When the image is rasterized, the image is subjected to various processes, such as a sharpness filtering process, a trapping process, an overprinting process, and a color process. In particular, in terms of a color process, a color conversion system using a color profile, which describes color reproduction characteristics of paper and a print device, is commercially available, since reproduced color significantly depends on the type of color material, such as toner, and the transfer medium, such as paper.
Color conversion techniques using a color profile have been proposed, for example, as disclosed in Japanese Patent Laid-Open No. 2004-64565. In this color conversion technique, ICC profiles defined by the ICC (International Color Consortium) are generally used. In particular, a technique using two profiles among the ICC profiles, namely, a source profile and an output profile, is widely used. The source profile describes the color characteristic of an input device and the output profile describes the color characteristic of an output device. A system using the source profile and output profile converts input data to a device-independent color space (PCS: Profile Connection Space) while referencing the source profile, and then converts the data to optimum color data for an output device while referencing the output profile.
Additionally, a device link profile is defined as another ICC profile. The device link profile holds a conversion table for directly converting input data to output data without using the PCS. Therefore, color conversion from input data to output data is carried out by referencing only one device link profile.
In a color conversion system of an image processing apparatus of commonly used color printers, the techniques using a source profile and an output profile are common. However, the types of color profiles initially installed in the image processing apparatus are limited. Therefore, some apparatuses allow a source profile and an output profile to be externally installed. Also, since creating a device link profile requires both a source profile and an output profile, some apparatuses can internally create a device link profile from a combination of a source profile and an output profile in the image processing apparatus.
Furthermore, some apparatuses implement a graphical user interface (GUI) in a printer driver in order to provide users with a user-friendly color processing path using a source profile and an output profile.
However, the printing process of known image forming apparatuses causes the problems described next.
Some known printers allow a source profile and an output profile to be externally installed and allow color processing via the PCS by selecting a source profile and an output profile at color processing time. On the other hand, a device link profile is created from a source profile and an output profile installed in the image processing apparatus.
This color conversion using a device link profile only provides the same effect as color conversion using a source profile and an output profile. In addition, some known apparatuses include a printer driver implementing a GUI that allows users to easily understand the color processing path using a source profile and an output profile. The color processing path is information as to which source profile should be used to convert data to image data of the PCS (profile connection space) and which output profile should be applied to the converted image data.
However, no known technology mentions an image processing apparatus allowing a user to install color processing tables (i.e., device link profiles) that have more features provided by tools of third vendors other than the vendor of the image processing apparatus so as to allow a color conversion processing using a variety of device link profiles, let alone an environment in which a plurality of device link profiles can be installed in an image processing apparatus and users can select an appropriate device link profile. Furthermore, no known image processing apparatus can notify a user of a color processing path in the case of using a device link profile created from a source profile and an output profile. Accordingly, it is more difficult for a user to master how to execute color settings using a device link profile compared to the widely used settings using a source profile and an output profile. Thus, an improved method of setting up such a system is required.